In the early 1900s, problems with existing adding machines led inventor William Hopkins to find ways for the adding machine to operate from a single set of digit keys. He placed the numbers on his machine to gears on a moveable carriage that was controlled by a moving handle. He applied for a patent in 1892.
The new machine was advertised at the National Banker’s Convention in 1896, and he started selling it in 1899. An office publication at the time hailed the machine as a “modern life preserver” that ended the drudgery of traditional bookkeeping. By January 1905, the company had sold over 3,400 machines. This ad appeared in a 1904 issue of Harper’s Magazine.